title: Gluteal muscle activation during running in females with and without patellofemoral pain syndrome.
abstract: BACKGROUND
  Hip and knee joint motion in the transverse and frontal plane during running may increase patellofemoral joint stress and contribute to the etiology of patellofemoral joint pain. We evaluated the association between these kinematics and the magnitude and timing of gluteus medius and maximus activity during running in females with patellofemoral pain. We also compared the magnitude and timing of gluteal muscle activity during running between females with and without patellofemoral pain.
  
  
  METHODS
  Twenty females with patellofemoral pain and twenty females without knee pain participated in this study. Three-dimensional running kinematics, gluteus medius and gluteus maximus onset time, activation duration, mean activation level, and peak activation level were recorded simultaneously. Gluteal muscle timing and activation level were compared between groups using independent t-tests. The association of gluteal muscle activation parameters running kinematics in females with patellofemoral pain was quantified using Pearson correlation coefficients.
  
  
  RESULTS
  Females with patellofemoral pain demonstrated delayed (P=0.028, effect size=0.76) and shorter (P=0.01, effect size=0.88) gluteus medius activation than females without knee pain during running. The magnitude and timing of gluteus maximus activation was not different between groups. Greater hip adduction and internal rotation excursion was correlated with later gluteus medius and gluteus maximus onset, respectively.
  
  
  CONCLUSIONS
  Neuromuscular control differences of the gluteal muscles appear to exist among females with patellofemoral pain during running. Interventions to facilitate earlier activation of these muscles may be warranted among females with patellofemoral pain who demonstrate altered running kinematics.
authors.affiliation: La Crosse Institute for Movement Science, Department of Health Professions, Physical Therapy Program, University of Wisconsin - La Crosse, 1725 State Street, LaCrosse, WI 54601, USA. willson.john@uwlax.edu
authors.forename: John D
authors.initials: JD
authors.lastname: Willson
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Kernozek
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Arndt
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Reznichek
authors.forename: J
authors.initials: J
authors.lastname: Scott Straker
mesh_terms: D005260:Female; D006621:Hip Joint / Q000503:physiopathology*; D006801:Humans; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000503:physiopathology*; D046788:Patellofemoral Pain Syndrome / Q000503:physiopathology*; D012420:Running; D055815:Young Adult